1. Field of the Invention
The present invention relates to a magnetic recording medium having excellent electromagnetic conversion characteristics and running durability with minimum clogging or dropout and without abrasion of the back coating layer. More particularly, the present invention relates to a magnetic recording medium having a feature in the composition of the coating layer (i.e. the back coating layer) formed on the resin side of the substrate opposite to the side on which a magnetic recording layer is provided.
2. Description of the Prior Art
Recently, magnetic recording media have been widely used in the fields of audio and video recording, computers, magnetic discs, etc. Accordingly, the amount of information to be recorded on magnetic recording media increases year after year, and there is an increasing demand for the improvement of the recording density of magnetic recording media.
As one of the conditions required for a magnetic recording medium for high density recording, it has been suggested to improve the coercive force and to make the medium thinner both from the theoretical and experimental points of view. There have been various proposals with respect to the compositions of the binder (binding agent), inorganic filler or lubricant for the back coating layer. However, conventional inorganic pigments have relatively large particle sizes, and they used to bring about drawbacks such that hard ones such as alumina or silica, tended to abrade e.g. tape guides during the tape running, or they were likely to impair the surface properties and to deteriorate the electromagnetic conversion characteristics.